> For the complete documentation index, see [llms.txt](https://docs.cheddar.vihan.org/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cheddar.vihan.org/docs/developing/api/primitives/func.md).

# func

The function class for Cheddar

## Arguments:

| name        | type     | description                                                                                                              |
| ----------- | -------- | ------------------------------------------------------------------------------------------------------------------------ |
| `arguments` | 2D array | (described below) this matrix described the arguments for the function. In the form of `[ ["arg_name", { <options> }] ]` |
| `body`      | function | (described below) the function body                                                                                      |

#### arguments matrix:

| name       | type              | default | description                                                                                         |
| ---------- | ----------------- | ------- | --------------------------------------------------------------------------------------------------- |
| `Type`     | `cheddar.class`   | n/a     | If provided, the argument is required to be of the given type                                       |
| `Default`  | `cheddar.class{}` | n/a     | If provided and the argument is not provided, it will be set to this rather than throwing an error. |
| `Splat`    | bool              | `false` | If provided, this and the following arguments will be combined into a `cheddar.array` object.       |
| `Optional` | bool              | `false` | If true, the argument will be `nil` if not provided                                                 |

#### function body:

| argument | description                                                                 |
| -------- | --------------------------------------------------------------------------- |
| first    | This is the **function's scope** as a `cheddar.scope`.                      |
| second   | This is a function which returns a variable's value, given a variable name. |

## Usage:

`-> (a, b = 0) a + b`, with api:

```javascript
new cheddar.func(
  [
    ["a", {}],
    ["b", {
        Default: cheddar.init(
          cheddar.number,
          10, 0, 0
        )
    }]
  ],
  function(scope, input) {
    return cheddar.init(
      cheddar.number,
      10, 0,
      input("a").value + input("b").value
    );
  }
)
```

## Internal Usage

### Execution:

```javascript
func.exec([
    arg1, arg2, ...
], scope)
```

`scope` will be set to `self` variable, if none, set to `null`.

### Arguments:

```javascript
func.args
```

the 2D matrix representing the arguments the function is requesting.